Optimizing Ecological Spatial Network Topology for Enhanced Carbon Sequestration in the Ecologically Sensitive Middle Reaches of the Yellow River, China
Round 1
Reviewer 1 Report
On the whole: The whole paper is too long and should be further condensed and simplified.
Abstract
1) Line 30： “optimization model(TFCO) model” to … should be changed to “optimization model(TFCO)”.
Introduction
1) In this part, the research progress at home and abroad needs to be supplemented.
2) Line 95-Line118: This paragraph should be rewritten; the results part should be delete from this part. I think the paragraph should focus on the objectives description of this research.
Results
1) This part is too long, please further condensed.
2) Line 372: “remaining around 40?” Please check it. How did the area of grass-shrub and forests change between 2000 to 2010 and between 2010-2020 year? Please specify it.
3) Fig.4 and Fig.5: How to further quantify the data by other forms of graphs, it is difficult to see where has changed in the current spatial distribution map, please supplement relative contents.
4) I think the Fig.4 can be deleted, the Fig.6 includes the Fig.4.
5) Fig.7: Please Check whether Figure 7 is labeled with errors, and the nodes of the figure does not correspond to Figure 6.
6) Line 436: The graph above the Line 436 should be deleted, it duplicated with Fig.7. The same as the graph above the line 461 and the graph above the line 530.
Discussion
1) Line 779-791: I think this part can be delete.
2) The discussion needs a comprehensive and concise description of the study results, and a comparison with existing studies.
References
1) The format of the references needs to be corrected according to the requirements of the journal.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The author used remote sensing data and land use data to investigate the relationship between the spatial distribution structure of vegetation and carbon sequestration function in the ecologically sensitive area of the middle reaches of the Yellow River. Based on MSPA, optimized CASA model, MCR model, complex network theory, and ecological spatial network theory, the temporal and spatial variations of the carbon sequestration function in the ecologically sensitive area of the middle reaches of the Yellow River were analyzed. The relationship between the carbon sequestration function and the topological indicators of the ecological spatial network for carbon fixation was also analyzed. A topology-function coupling optimization model was constructed to explore the coordination between vegetation structure and carbon sequestration function, and to propose increasing the ecological source function and the number of ecological corridors, optimizing their temporal and spatial distribution, and achieving the coupling optimization of carbon sequestration capacity and ecological structure. The research results can provide information and support for the scientific establishment of land use planning and ecological security pattern in ecologically sensitive areas. This study is of great significance and provides a scientific basis for improving the ecological stability and carbon sequestration function of the ecologically sensitive area of the middle reaches of the Yellow River. The article is logically clear, beautifully illustrated, well expressed, and innovative. However, there are some issues that need to be addressed:
1. The reviewer suggests that the image citation is unnecessary and recommends its removal, such as Fig.7 in line 436.
2. The flow chart of the TFCO model needs further optimization.
3. The literature review is too weak.The authors need to introduce the existing research of ecological spatial network. And explain the reasons for the method chosen in this paper.It is recommended that the author add more international literatures to improve this part.
4. The paper contains many initialisms. When they first appear in the paper, the authors should provide their full name. For example, "NDVI" in line 108 of the paper.
5. In section 3.1.1, the authors should quantify the number of different types of ecological source areas and their changes over 20 years, and display them visually in the form of charts and graphs.
6. When constructing the ecological space network, the authors introduced the theory of complex adaptive systems. Please simplify the introduction of the theoretical content and supplement the applicability of the theory in the ecological space network.
7. The authors should further refine their findings and innovations in the discussion section and summarize them based on citations of previous studies.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
In general, the work is interesting and the experience of identifying key areas and ecological corridors from the point of view of ecosystem functions should be published. At the same time, questions remain.
The term "ecological source" cannot be considered correct in the sense that the authors attach to it. More correctly - a source of environmental (ecological) services.
Authors should pay attention to the design of the text. All figures require detailed explanations - should be clear without main text.
The main questions that are not reflected in the methodology are:
1. Have there been ground-based studies to assess phytomass and carbon balance? 2. a significant part of the carbon stock of terrestrial ecosystems is in the soil. Whether this stock was taken into account in the corresponding models (calculations). If "yes" - then - "how"
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
The problem discussed in the paper is absolutely actual and is in frame of main stream of modern study of the Carbon Sequestration Capacity. The authors consider certain factors and development of carbon sequestration in ecosystem in the area of the Yellow River in China. They establish a corresponding model for that in frame of the eco-space network taking into account the plant light utilization efficiency. The consideration displays in a very ambitious presentation with proposition of some optimization strategy based on the data over the past 20 years under different conditions for certain areas. The principal item for such approach is to recognize the level of ecological resistance and to determine the number of ecological corridors between nodes of the networks. The authors declare this goal.
REMARKS.
1. As to the title of the paper, the unit is very long with some collection of popular terminology but is not informative in the key word aspect.
Should be modified in more focused form.
2. It is very difficult to understand sometimes the idea of the author consideration due to presence of many verbal shortening transcriptions in the text even in formulas (e.g. see lines 160, 166, 184, 191,194, 207-209, 215, 258, 285, etc) described without traditional a single letter parameter utilization in common theory. Moreover, in the paper does not develop the real (and not fictitious) theory and mathematical/computer modeling and simulations, but is just presented the verbose blocks and graphical schemes (see Figs.2, 3) with unclear the unit symbols (e.g. lines 293, 305, 720, 721, in Tables 1-3), but with strange accuracy, e.g. 215,310.73tC/yr(!) – line 877. Should be corrected and rewritten.
3.What does it mean the Fig. 7 and double repeated images between lines 434-437, as well is for the Fig. 8 and between lines 459-462 ?
4. It is desirable to justify the necessity and advantages of calculating phytoproductivity using MODIS data in comparison with other methods of its assessment. Why don't the authors use ready-made MODIS products containing parameters of vegetation productivity in carbon units.
5. It is necessary to describe in more detail and clearly the meaning and structure of ecological corridors in the regulation of carbon sequestration processes. What new information can be obtained using this approach.
6. General deficiency of the paper content is the presentation of many database and verbal notions but without a real analytical conclusive consideration, clear and precise discussion and explanations in respect of the author approach, especially with numerical topological metrics (the topology, in the authors a specific understanding, mentioned in less than in 10 lines (267-276) in section 2.2.3 only(?) but further in section 2.4 and in divisions 3-4). Even when using well-known models, it is necessary to justify their use for a particular study.
CONCLUSION.
The paper needs major corrections and principal modification with detailed analytical comments in accordance with above remarks.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have made great efforts to revise the manuscript. Please check the text carefully again. For example: Line72-101： Please note the font size. Line 388-399： Please check it.
Reviewer 4 Report
The paper is of scientific interest. The authors use modern methods of processing and interpreting the results. I am satisfied with the answers to my questions and comments. I believe that the paper can be accept in its present form.
